Semiconductor nanocrystals are nanometer-scale fragments of the corresponding bulk crystals, and have properties between those of bulk crystals and molecules. The size-dependent emission is an attractive property of semiconductor nanocrystals. For example, differently sized CdSe nanocrystals can be prepared that emit from blue to red light, with comparatively pure color emissions. These nanocrystal-based emitters can be used for many purposes, such as for solid-state-lighting, solar cells, lasers, and so on.